Material and method applicable to the treating of hides, skins, and leather



Patented Apr. l7, 1934 UNITED STATES PATENT OFFICE MATERIAL AND METHOD APPLICABLE TO THE TREATING or HIDES, SKINS, AND

LEATHER No Drawing. Application March 16, 1933.

Serial No. 661,190

22 Claims. (Cl. 149-72) This invention relates to materials and methods applicable to the treatment of hides,skins, and leather. scribed with reference to degreasing operations upon skins, it is to be understood that the invention and various important characteristics thereof may have other applications and uses.

In accordance with one of the methods of degreasing skins still commonly practised, the skins are piled upon the lower platen of a press, care being taken to fold the shanks in upon the adjacent fiank portions of each skin so that the latter in its-folded condition is substantially rectangular in shape. In the pile the butt and neck portions of each skin are superposed upon the butt and neck portions, respectively,-of the skin next subjacent thereto. By this method of preparing skins for a pressing operation the thicker butt and neck portions are subjected to the maximum pressure, this being of advantage since the butt and neck portions of the skins contain the greatest amount of fat or grease. After the pile of skins has thus been built up on the platen of the press, the latter is operated to apply pressure very gradually, since the work at this period may be easily damaged. As will be readily understood, the preparation of the skins for the pressing operation and the pressing operation itself require very considerable expenditure of time and labor. Furthermore, in spite of the exercise of care in the piling of the skins and in the application of pressure, the results are not particularly satisfactory. As a matter of fact, while much grease is expressed from the skins under this treatment, a great deal still remains, particularly on the surfaces 'of the skins. Hence kerosene or other similar substance must be used to remove the surface grease, but only after the pressed cake of skins has been drummed for a long time in warm salt try, the skins are introduced into vats with con-' siderable quantities of kerosene or other special degreasing fluids such as naphtha. If continued for a sufllcient length of time, this treatment is While the invention will be de-" It is not uncommon to rupture the and then washing with a salt solution in very large quantities, the washings being repeated three or four times. The results obtained by this method are variable and only moderately satisfactory. Ordinarily not enough of the fat or grease is removed from the skins to produce the finest work. Not infrequently the fat or grease will show up in smooth plating operations in which a hot plate is used. Usually skins degreased by this method are suitable only for 001- oring with pigment since the latter may be made with a suflicient body to provide an effective covering.

Objects of this invention are to obviate the objections to degreasing methods as heretofore practised and more particularly to avoid all injury to the hide or skin substance. Further objects of the invention are to speed up the degreesing operation, increase its efliciency, and, more especially, to provide a much better product.

To these ends and in accordance with an important characteristic of the invention, the skins are subjected to treatment by a composition comprising a liquid hydrocarbon solvent of fat or grease mixed with a non-drying oil of such nature that the mixture will form an emulsion with water. By the term oil is meant a glyceride of one or more of the fatty acids. A preferred mixture contains an oil, of animal or vegetable origin, commonly employed in fatliquoring operations on tanned skins. Such an oil will expedite penetration of the liquid hydrocarbon into the skin substance. A fatliquoring oil has the further advantage of forming very readily an emulsion with water, this being especially true of sulphonated oils, so that, upon adding. water to skins undergoing agitation with the described mixture, extraction of the fat or grease from the skins in an emulsified form is facilitated to a remarkable degree, the emulsion having as elements the fat or grease from the skin, the liquid hydrocarbon, the oil, and water. Ordinarily kerosene will be selected as the hydrocarbon. constituent of the degreasing preparation because of its relatively low cost, and since it is safer in use than gasoline or naphtha.

In accordance with a preferred manner of prm are subjected to the action of thedescribed degreasing liquid for a time sufiicientto secure penetration of the skins by the desired amount of degreasing liquid after which the skins thus treated are subjected to violent agitation with water to form an emulsion. During the formation of the emulsion, fat or grease of the skins is extracted therefrom in an emulsified form with the de-' scribed degreasing preparation and water, the extraction of the fat or grease in emulsified form taking place concurrently and concomitantly with the penetration of the water into the skin substance.

Conveniently, the described degreasing liquid will be caused thoroughly topenetrate the skins undergoing treatment by drumming the skins in the desired amount of such liquid. After a suitable interval water is added, preferably periodically, to form an emuision; the emulsion consisting not only .of the degreasing liquid and water but of the fat or grease coming out of the skin. We have found that such an emulsion, of which the fat or grease from the skin constitutes an important and essential component, is formed most satisfactorily if salt (sodium chloride),-

heretofore almost universally used in degreasing operations, be omitted. It is important also that the temperature be maintained substantially below 100 Fahrenheit if the emulsion is to be formed in a satisfactory manner. Under these conditions an emulsion is promptly formed and,

through the action of the emulsion, the latter is discharged and the skins are washedwith pure water introduced in quantity into the drum, this washing, however, being restricted to a very 'short period of time and being just suflicient to remove the greater part of theemulsion from the surfaces of-the skins. Following this superficial washing, a salt water washing is carried out at intervals of about fifteen minutes, the wash waterbeing discharged at these intervals and fresh salt water added until the skins are substantially free from all surface fat or grease and otherwise in a satisfactorily degreased condition. I

These and other important characteristics of the invention will now be described in detail in the specification and then pointed out more particularly in the appended claims.

In degreasing operations designed particularly for *thetreatment of sheep skins, the latter are taken from the pickle and drummed in a degreasing liquid, preferably made up of kerosene and a fat liquor in the amount of six ounces of kerosene to one-half ounce of fatliquor per skin. The fatliquor may be any-one, or a combination of several, of the well-known preparations used extensively in fatliquoring leather and is commonly either an oil (as defined above) or a sulphonated.

oil, capable of forming-an emulsion'with water. This preliminary treatment is continued for about thirty minutes during which the skin's are thor-, oughly drummed in the liquid. They are then removed from the drum and fleshed in an ordinary commercial type of fleshing machine. Fleshing is advantageous at this point in the treatment of the skins since it removes some of the looser fat-containing tissue from the flesh surfaces of the skins. Also in the. fleshing oper- 1,964,798 tising this novel method of degreasing skins, they ation there is a distinct tendency to distribute the fat more evenly in the skin and to express some of it. If the fleshing operation be not performed, a substantial increase in the amount of degreasing liquid must be -made over the amounts herein given. It will be understood that the kerosene penetrates the hide or skin substance much more v rapidly and evenly if the skins contain a minimum amount of moisture. Of course the skins should have no dry spots when removed from the shipping or storage casks. If such dry spots be observed, they should be first dampened -with water and the skins drummed for a few minutes before adding the degreasing liquid. In' the case of skins containing an unusual amount of fat or grease they may be allowed to remain in this degreasing liquid overnight before being fleshed. a

After flashing, the skins are introduced'into a drum with one gallon of the degreasing liquid to each dozen skins and drummed for one hour at a temperature of about F., the degreasing liquid conta'ning kerosene and an oil or a sulphonate' thereof in the proportion of about 12. t 1. Excellent results have been obtained using, for a degreasing liquid, kerosene mixed with any one or more of the following fatliquoring oils viz., codliver oil, neats-foot oil, moellen degras, sulpho nated cod-liver oil, sulphonated neats-foot oil, castor oil, coconut oil, olive-oil, and a commercial f atliquor containing a liquid hydrocarbon; At the end of an hour's drumming in the degreasing liquid, ordinary pure water (i. e. without salt) is introduced into the drum in the amount of about eight ounces for each skin, this amount being added at intervals of fifteen minutes thereafter for two-hours, This means that the eight ounces per skin is added eight times so that the total amount is sixty-four ounces per skin, Excellent results are obtained by thus adding the water in small amounts at the intervals described. An emulsion is formed with the grease and the described degreasing liquid, this emulsion increasing in amount with the addition of water and growing in amount through the extraction of a fat emulsion from the skins. It is to be understood that the water may be added all at once or in amounts and at intervals differing considerably from those specified. In a drum containing three dozen sheepskins to which degreasing liquid and water have been added in the amounts mentioned, a remarkable amount of fat emulsion is withdrawn at the end of the three-hour period, this amount be-' ing in the cited case eleven gallons of a thick white fat emulsion.-

Afterthe removal of the fat emulsion following the three-hour period of drumming, the skins are subjected to a washing operation in pure water in the amount of one gallon for each dozen skins.

'Thswashing is a very brief one, about a minute in extent, after which the wash water is discharged from the drum, the purpose being to remove emulsion from the surfaces of the skins. There is immediately added a washing liquid of salt (sodium chloride) water of about 4 Bkr., in the amount of one gallon for each dozen skins, after whch the drumming is continued for about flf- The skins are now ready for tanning.

On inspection, the skins will be found to be free from surface fat or grease, although fat or grease in a desirable amount is still present in the skin'substance but very evenly distributed. It will be understood that all fat or grease should not be removed from the skins since this would be to remove all lubricating substance, thus leave ing the skins dry and flat. As a matter of fact, some fat or o'l is added to the skins after tanning. Skins with the proper amount of fat or oil will have the proper feel of leather after tanning and have the desired strength to resist very substantial tension such as that commonly applied in working operations upon leather as, forv instance, in shoemaking. Moreover, the skins degreased by the method described herein will, when tanned, have the requsite softness and thickness and will stand smooth plating or embossing operations without bringing any fat or grease to the surface of the skin.

Having thus described'our invention what we claim as new and desire to secure by Letters Patent of theUnited States is:

1. A composition for use in degreasing skins whch comprises 'a mixture .of aliquid hydrocarbon, and a non-drying oil capable of forming an emulsion with water.

2. A composition for use in degreasing skins which comprises a mixture of a liquid hydrocarbon, and a non-drying oil capable of forming; an emulsion with water, in the proportion of about twelve to one. r

3. A composition for use in degreasing skins comprising a mixture of a liquid hydrocarbon, and a fatliquor having the property of forming an emulsion with water. 4. A composition for use in degreasng skins comprising a mixture of a liquid hydrocarbon, and

a fatliquor having the property of forming an emulsion with water-,in the proportion of about twelve to one.

5. A composition for use in degreasing skins compr. sing a mixture of kerosene and a non-drying vegetable oil. I

6. A composition for use in degreasing skins which comprises a mixture of kerosene and an animal oil. P

,7. 'Acomposition for use in degreasing skins which comprises a mixture of kerosene and a sulphonated fa-tl'quor. v

8. A composition for use in degreasing skins which comprises a mixture of kerosene, and a fatliquor having a liquid hydrocarbon as a constituent thereof.

9. That improvement in methods of degreasing skins which comprises subjecting the skins to.

treatment by a degreasing liquid capable of dissolving grease and forming an emulsion with water, and adding water while theskins are being violently agitated, thereby emulsifying the grease and removing it from the skins.

10. That improvement in methods of degreasing skins which comprises subjecting the skins to treatment with a mixture of a liquid hydrocarbon and a non-drying oil until the skins have taken up the desired quantity of themixture, and then violently agitating the treated skins with water to form an emulsion during the formation of which fat or' grease of the skins is gradually removed therefrom.

11. That improvement in methods of degreasing skins which comprises subjecting the skins to treatment with a mixture of a liquid hydrocarbon and a non-drying oil until the skins have taken during the continued drumming thereof.

up the desired quantity of the mixture, and then violently agitating the treated skins with water free from salt to form an emulsion during the formation of which fat or grease of the skins is gradually removed therefrom. I

12. That improvement in methods of degreasing skins which comprises subjecting the skins to treatment with a mixtureof a liquid hydrocarbon and a non-drying oil until the-skins have taken up the desired quantity of the mixture, and then violently agitating the skins with water, free from salt, at a temperature of about F. to form an emulsion during the formation of which fat or grease of the skins is withdrawn therefrom.

13. Thatimprovement in methods of degreasing skins which comprises subjecting the skins to treatment with a mixture of a liquid hydrocarbon and a. non-drying oil until the skins have taken up the desired quantity of the mixture, and then violently agitating the skins with water at a temperature substantially below 100 F. to form an emulsion during the formation of which fat or grease of the skins iswithdrawn therefrom.-

14. That improvement in methods of degreasing skins which comprises drumming the skins in a degreasing liquid capable of dissolving grease 'and forming an emulsion with water, and adding water to form an emulsion while the drumming continues, thereby removing the greasefrom the skins concomitantly with the formation of the emulsion.

15 That improvement in methods of degreasing skins which comprises drumming the skinsin the desired amount of a degreasing liquid capable of dissolvinggrease and forming an emulsion with water, and adding ordinary pure water in small amounts at intervals during the drumming operation to form an emulsion of the grease and the degreasing liquid for the extraction of the fat or grease from the skins. I

16. That improvement in methods of degreasing skins which comprises drumming the skins in a degreasing liquid of kerosene and a fatliquor in the desired proportions until the skins have been thoroughly permeated with the degreasing liquid to dissolve the grease, and adding ordinary pure water' to form an emulsion of the degreasing liquid and fat whereby the latter is extracted from the skins during the continued drumming thereof.

17. That improvement in methods of degreas k ing skins which comprises drumming the skins in a degreasing liquid of kerosene and a fatliquor in the desired proportions until the skins have been thoroughly permeated with the degreasing liquid to dissolve the grease, and adding-ordinary pure water in small amounts at intervals to form an emulsion of the degreasing liquid and fat whereby the latter is extracted from the skins 18. .That improvement in methods of degreasing skins which comprises drumming the skins in a degreasing liquid, capable of dissolving grease and forming an emulsion with water, at a temperature substantially less than 100 F., and adding ordinary pure water' in' small amounts at intervals while the drumming is continued thereby forming an emulsion of the fat and the degreasing liquid whereby the latter are extracted from the skins.

' 19. That improvement in methods of degreasing skins which comprises drumming the skins in a degreasing liquid capable of dissolving the I grease in the skins and of forming an emulsion with water, addingwater in small amounts at 150 intervals thereby forming an emulsion during continued drumming of the skins, discharging the emulsion thus formed at the proper time, and then washing the skins with salt solution employed in repeated washings until the desired amount of emulsion has been removed from the skins.

20. That improvement in methods of degreasing skins which comprises drumming the skins in a degreasing liquid capable of dissolving grease in the skins and of forming an emulsion with water, adding water to form an emulsion during continued drumming of the skins, formation of the emulsion taking place concomitantly with extraction of grease from the skins, discharging the emulsion thus formed at the proper time, then washing the skins with salt solution employed in repeated washings until the desired amount of emulsion has been removed from the skins, and maintaining the temperature of the liquids within the drum at a temperature substantially below 100 F. throughout all of the drumming operations.

in the desired-proportions until the skins have been thoroughly permeated with the degreasingliquid, then fleshing the skins, placing them again in the drum with an additional amount of said degreasing liquid, and adding pure water to form an emulsion during continued drumming, whereby the grease is extracted from the skins during the continued drumming thereof.

JOHN H. CONNOR. MATTHEW M. MERRITT. 

